Wilder was due to make the fourth defence of his crown against Povetkin in Moscow next weekend but the WBC announced on Friday that the challenger had shown an "adverse result" for meldonium when tested by the Voluntary Anti-Doping Association on April 27.

And the organisation said on its official Twitter account last night that the fight which had been scheduled for next Saturday was off.

The winner of the showdown had been tipped for future bouts against British pair Tyson Fury, the WBA and WBO champion, and IBF belt holder Anthony Joshua.

"I'm very disappointed that due to Povetkin's failed drug test the fight is not going to happen," Wilder said in a statement.

"I had worked very hard to prepare myself for this important title defence, spending the last two weeks training in England to get accustomed to fighting in Europe.

"I wanted to give the fans a great show, but we understand the WBC's position that the fight occur on an even playing field.

"This is a huge disappointment and a setback to my goals in boxing. I want to be an active heavyweight champion and it is still my goal to collect all the belts and become the undisputed heavyweight champion of the world."

Tennis player Maria Sharapova has been provisionally banned since March after testing positive for the drug - added to the World Anti-Doping Agency's list of prohibited substances on January 1 - at the Australian Open.